An SCCM Task Sequence fails mid-deployment with 0x80070490 on reviewing the SMSTS.log file, the location of this log files depends so please consult the following blog;
In my SMSTS.log file it was specifying the error "Unable to find a Windows system root at X:\. Element not found. (Error 80080490); Source: Windows)". After a bit of further research it turns out this is related to the Windows WIM file index.
My Task Sequence was configured to use 1-1 so I used the following command;
Dism /Get-WinInfo /WimFile:D:\PathtoWim.wim
This printed the images indexes in the current WIM file. You will notice from the screen shot that 1-1 was reporting a description of "undefined". This made sense, so I though I would check within the Configuration Manager console.
Browse to Software Library\Overview\Operating Systems\Operating Systems Images and right click on the image that is being deployed via the Task Sequence select Properties.
From the Properties window click on the Images tab and select 1-1 you will notice that most of the properties are actually blank.
If you do the same again and choose 2-2 the fields are now populated.
Now that I had determined the cause of the issue the next step was to edit the Task Sequence, browse to Software Library\Overview\Operating Systems\Task Sequences and right click on the Task Sequence and select Edit. Click on the step within the Task Sequence that installs the operating system and ensure the Image drop down is set to 2-2 when I first checked mine was obviously set to 1-1.